Synthesis and chemical transformation of Ni nanoparticles embedded in silica. Issue 47 (28th November 2017)

• Record Type: Journal Article
• Authors: Lynch, Brian B.; Anderson, Bryan D.; Kennedy, W. Joshua; Tracy, Joseph B.
• Is Part Of: Nanoscale. Volume 9:Issue 47(2017)
• Page Start: 18959
• Page End: 18965
• Publication Date: 2017-11-28
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/c7nr06379b
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : Overcoating Ni nanoparticles with SiO2 etches, oxidizes, and embeds them in SiO2, which provides stability during oxidation and reduction. Abstract : Ni nanoparticles (NPs) catalyze many chemical reactions, in which they can become contaminated or agglomerate, resulting in poorer performance. We report deposition of silica (SiO2 ) onto Ni NPs from tetraethyl orthysilicate (TEOS) through a reverse microemulsion approach, which is accompanied by an unexpected etching process. Ni NPs with an average initial diameter of 27 nm were embedded in composite SiO2 -overcoated Ni NPs (SiO2 -Ni NPs) with an average diameter of 30 nm. Each SiO2 -Ni NP contained a ∼7 nm oxidized Ni core and numerous smaller oxidized Ni NPs with diameters of ∼2 nm distributed throughout the SiO2 shell. Etching of the Ni NPs is attributed to use of ammonium hydroxide as a catalyst for deposition of SiO2 . Aliquots acquired during the deposition and etching process reveal agglomeration of SiO2 and Ni NPs, followed by dissociation into highly uniform SiO2 -Ni NPs. This etching and embedding process may also be extended to other core materials. The stability of SiO2 -Ni NPs was also investigated under high-temperature oxidizing and reducing environments. The structure of the SiO2 -Ni NPs remained significantly unchanged after both oxidation and reduction, which suggests structural durability when used for catalysis.